This invention relates to the delivery of bioactive compounds to an organism, and in particular to methods and apparatus for the delivery of bioactive compounds by implanting into the organism an organized tissue producing the compounds.
One of the primary therapies used to treat disease is the delivery of bioactive compounds to the affected organism. Bioactive compounds may be delivered systemically or locally by a wide of variety of methods. For example, an exogenous source (i.e., produced outside the organism treated) of the bioactive compound may be provided intermittently by repeated doses. The route of administration may include oral consumption, injection, or tissue absorption via topical compositions, suppositories, inhalants, or the like. Exogenous sources of the bioactive compound may also be provided continuously over a defined time period. For example, delivery systems such as pumps, time-released compositions, or the like may be implanted into the organism on a semi-permanent basis for the administration of bioactive compounds (e.g., insulin, estrogen, progesterone, etc.).
The delivery of bioactive compounds from an endogenous source (i.e., produced within the organism treated) has also been attempted. Traditionally, this was accomplished by transplanting, from another organism, an organ or tissue whose normal physiological function was the production of the bioactive compound (e.g., liver transplantation, kidney transplantation, or the like). More recently, endogenous production by cells of the affected organism has been accomplished by inserting into the cells a DNA sequence which mediates the production of the bioactive compound. Commonly known as gene therapy, this method includes inserting the DNA sequence into the cells of the organism in vivo. The DNA sequence persists either transiently or permanently as an extra-chromosomal vector (e.g., when inserted by adenovirus infection or by direct injection of a plasmid) or integrates into the host cell genome (e.g., when inserted by retrovirus infection). Alternatively, the DNA sequence may be inserted into cells of the host tissue or an another organism in vitro, and the cells subsequently transplanted into the organism to be treated.